Set Appliance State:

Mains Power Off
Set Multimeter to AC Voltage Set meter to measure AC Volts
CH Demand
Remove lower facia panel
WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure
Mains Power On

Measurement:

Measure voltage across connection (Marked Ls) and the neutral (marked N) on connector block ST2. The connector block is situated at the bottom L/H side of the PCB.